The invention refers to a mixer valve of the type required particularly for heating and hot water installations, integrated into the housing of a circulation pump in such a manner that a wheel-shaped mixer actuator, which is provided with blades, and a running wheel of the circulation pump are arranged to be coupled for positioning the mixer/actuation. The mixer/actuation and the running wheel, for example, have flush axles and the mixer actuator and the running wheel drive of the circulation pump can be axially engaged by means of a controllable coupling by which they contact one another. Alternatively, a coupling can be inserted and retracted.
According to such a construction, a mixer valve can be built in a particularly space-saving manner in conjunction with a circulation pump, since the compact design allows direct control of the warm and cold water to be circulated. In addition, a common drive for the actuator of the mixer valve and for the circulation pump also facilitates the control processes, allowing correct control of the outflow and return flow of the heating water, since both devices form one unit.
Accordingly, the present invention concerns a further development of such a combination of mixer valve and circulation pump, of which the basic structure has previously been disclosed by the present inventor, as shown in DE-PS No. 19 58 277, dated Oct. 7, 1971.
The invention is based on an insight gained by the inventor, that it is extremely damaging for heating installations, if returning heating water is at a temperature below a given minimum temperature, preferably in the 40.degree.-45.degree. C. range. In the case of too low a temperature, thermal stresses occur in an operating heating installation, and will cause deterioration.
An object of the invention is to provide a mixer valve which, in combination with a circulation pump, is built in such a manner that in any position of the actuator, independently of external influences and particularly also in case of a power failure, a return temperature lower than the specified minimum temperature of the return water is reliably prevented. This is accomplished independently of operational conditions, including for instance, if several cooled heating elements in a heating system are suddenly started up, when the heating is just started and also when the heating has already been running for some considerable time.
This object is achieved according to the invention by means of a mixer valve with a certain permanent uncontrollable bypass for a portion of the water moving through the mixer/actuator.
In the mixer valve according to the invention, the actuator of the valve proper is designed in such a manner that even in a position where a path through the actuator is nominally blocked in any direction, namely independent of the position of the actuator or its blades, there is still a water path. The bypass volume can be small compared to the total through-flow, namely in the order of magnitude of 10% of the water through-put, so that the (cool) water returning from the heating circuit to the valve is mixed with (hot) water coming from the boiler and is thus brought up to the desired higher return temperature before returning into the boiler.
Mechanically, there are several ways of achieving this mixing, which is to be provided according to the invention, namely of the heating water coming from the boiler with the cooled return water coming from the heating circuit. For example, one could envision providing the mixer valve with a "bypass" passage which renders possible a return of heating water into the return circuit.
Thereby, mixer valve, distributor, and pump are built in a particularly compact manner, so that the unit can be installed even in basements with low ceilings.
However, it is particularly advantageous if mixing is accomplished by keeping the width of the mixer actuator blades less than the clearance width therefor in the interior of the mixer. As a result, independent of the position of the mixer actuator, there can always be, between blade and wall, a passage of water. The passing water then self-adjusts to buffer the temperature drop between one mixer chamber and the other.
According to a further development of the invention, an idle position is preferably assigned to the mixer valve. In the idle position there is, on one hand, a direct connection between the boiler outflow and the heating water output and, on the other hand, between the heating water return and the boiler return. The idle position is always assumed when, for any reason, the circulation pump becomes inoperative, e.g., in case of a power failure. Contrary to all other installations including circulation pumps, this installation guarantees that circulation around the whole heating loop will constantly be driven and provided with hot water. This results from gravity and the temperature differences of water in the loop. The advantage of the mixing process between hot water and return water is retained without change.
Since the idle position must be set in case of a power failure, it must be manually adjustable. For this reason, an additional further development provides a particularly simple coupling between a manual drive and the drive shaft of the mixer actuator by means of an activating shaft. The coupling between the drive shaft of the mixer/actuator and the activating shaft consists of a shaft guided in a coupling part and rotatable from the outside, defining a half-shaft in the coupling area. This establishes a rigid connection between the two parts to be coupled, namely connection by nonrotatable engagement of complementary shapes, or a disconnection, whereby the disconnected part can slide freely over the flat portion of the half-shaft.